It is generally known in roller bearing technology that the radial roller bearings which are used most frequently are single track and multiple track groove ball bearings, since they are distinguished above all by an equally high radial and axial loadbearing capacity and have the highest rotational speed limits of all radial bearings on account of their low friction. The groove ball bearings comprise substantially an outer bearing ring and an inner bearing ring and a number of balls, which are arranged between the bearing rings as rolling bodies, which roll groove-shaped raceways in the inner side of the outer bearing ring and in the outer side of the inner hearing ring and which are guided at uniform spacings from one another by a bearing cage. Here, the radial ball bearings are filled with the balls by the eccentric mounting method which has been disclosed by DE 168 499 and in which the two bearing rings are arranged eccentrically with respect to one another and the free space which is produced as a result between the bearing rings is filled with the balls.
However, it has been shown in practice that limits are nevertheless placed on groove ball bearings of this type in relation to the loadbearing capacity of the bearing on account of the low maximum number of balls which can be installed and/or the low maximum filling level of approximately 60%. In the past, a multiplicity of solutions were therefore proposed, in which the number of balls and, therefore, the loadbearing capacity of groove ball bearings was to be increased, for example, by the arrangement of filling openings in the raceways. Moreover, another possibility to increase the number of rolling bodies on a radial roller bearing has been disclosed by DE 43 34 195 A1. In this radial roller bearing, which is formed per se as a single track groove ball bearing, the rolling bodies are not formed by balls, but rather by what are known as ball rollers, which are configured as balls with two side faces, which are flattened symmetrically from a basic ball shape and are arranged parallel to one another. Here, the width of the ball rollers between their side faces is smaller than the spacing between the inner side of the outer bearing ring and the outer side of the inner bearing ring. As a result, during filling of the bearing, the ball rollers can be introduced into the bearing, axially with respect to the bearing, through the spacing between the inner ring and the outer ring and can then be rotated by 90° into the raceways of the bearing rings. Since smaller spacings can be achieved between the individual rolling bodies as a result of this mounting method, a higher number of rolling bodies overall can therefore be introduced into the radial roller bearing.
However, since, in ball roller bearings of this type exact axial guidance of the ball rollers is required and, above all, automatic rotation of the ball rollers transversely with respect to the running direction is to be avoided during bearing operation, a plurality of embodiments of corresponding bearing cages are also proposed in the document cited last. Here, one cage embodiment, which is particularly suitable for applications with low noise requirements, is a plastic snap action cage which is open on one side and comprises a circumferential solid-walled side ring with pocket webs which extend axially away from it on one side and merge at the level of a plane which is defined by the center points of the ball rollers into two elastically yielding pocket tabs. Here, the pocket tabs are spaced apart from one another by an intermediate space and form in pairs a plurality of cage pockets which spatially surround the running faces of the ball rollers.
However, it has proven disadvantageous that the entire kinematic behavior of the ball rollers which occurs at different bearing loadings has not been taken into consideration in a snap action cage which is configured in this way. It has thus been determined, for example, that ball rollers as rolling bodies in radial roller bearings roll without offsetting movements stably in their raceways at relatively high speeds and uniform load on account of the gyroscopic effect which occurs, and do not require any axial guidance by the bearing cage. If, however, the bearing rotational speed drops below a permissible minimum rotational speed or the bearing is suddenly accelerated greatly, what is known as a tumbling effect occurs, in particular, in the loadfree zone of the bearing. During the tumbling effect, the ball rollers tend to roll in their raceways in an undulating manner transversely with respect to the running direction. Here, first contact occurs between the running faces of the ball rollers and the side ring of the snap action cage. By way of this contact, friction heat is generated and the contact is the cause of a disadvantageous rise in the operating temperature in the radial roller bearing. Here, the friction between the ball rollers and the bearing cage and the tumbling movements of the ball rollers can become so pronounced that the ball rollers ultimately even snap out of their cage pockets which are open on one side, via the elastically yielding pocket tabs, and stand transversely with respect to their raceways, with the result that destruction of the bearing cage and premature failure of the bearing occur. The ball rollers within a bearing cage of this type likewise have no possibility to orient themselves to the respective contact angle in the case of mixed radial and axial loading of the bearing, without contact between the ball rollers and the side ring of the snap action cage and the resulting disadvantageous consequences likewise occurring.